Effect of Fibrous Mineral Dusts on the Aryl Hydrocarbon Hydroxylase Activity of Rat Alveolar Macrophages in Vitro

The aryl hydrocarbon hydroxylase (AHH) is considered as a key enzyme in the metabolism of carcinogenic polycyclic aromatic hydrocarbons (PAH). It catalyses the formation of epoxides (Heidelberger 1975) and further of diol-epoxides, which are regarded as “ultimate carcinogenes” (Buening et al. 1978). The activity of AHH correlates with the carcinogenic activity of the tested PAH in most of the cases (Kinoshita and Gelboin 1972). In epidemiology the synergistic interactions between the exposure to asbestos and cigarette smoke is commonly known (Selikoff et al. 1968; Hammond et al. 1979). This combined effect leads to an increased risk of lung cancer. An increase of carcinogenic activity of PAH can also be observed in animal experiments, by simultaneous application of PAH and exposure to particles (Lakowicz and Hylden 1978). The adsorption process of PAH to fibre and other particles leads to an enhanced biological availability of PAH (Kandaswami and O’Brien 1983; Lakowicz and Bevan 1979). The intention of our examinations was to test possible fibre/PAH interactions in intact alveolar macrophages on the basis of AHH-activity.